Following Black Hole Scaling Relations through Gas-rich Mergers
We present black hole mass measurements from kinematic modeling of high-spatial resolution integral field spectroscopy of the inner regions of nine nearby (ultra-)luminous infrared galaxies in a variety of merger stages. These observations were taken with OSIRIS and laser guide star adaptive optics on the Keck I and Keck II telescopes, and reveal gas and stellar kinematics inside the spheres of influence of these supermassive black holes. We find that this sample of black holes are overmassive (~10^(7–9) M⊙) compared to the expected values based on black hole scaling relations, and suggest that the major epoch of black hole growth occurs in early stages of a merger, as opposed to during a final episode of quasar-mode feedback. The black hole masses presented are the dynamical masses enclosed in ~25 pc, and could include gas which is gravitationally bound to the black hole but has not yet lost sufficient angular momentum to be accreted. If present, this gas could in principle eventually fuel active galactic nucleus feedback or be itself blown out from the system.
© 2015 The American Astronomical Society. Received 2014 September 22; accepted 2015 February 3; published 2015 April 16. A.M.M. acknowledges useful conversations with George Privon, Sebastian Haan, Tiantian Yuan, Stephanie Juneau, Kevin Schawinski, David Rosario, and Simona Gallerani. We enthusiastically thank the staff of the W. M. Keck Observatory and its AO team, for their dedication and hard work. Data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory and the Keck II Laser Guide Star AO system were both made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to extend special thanks to those of Hawai'ian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, the observations presented herein would not have been possible. This work was supported in part by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement AST 98-76783. This material is based in part upon work supported by the National Science Foundation under award number AST-0908796. Facility: Keck:I (Laser Guide Star Adaptive Optics OSIRIS), Keck:II
Published - 0004-637X_803_2_61.pdf
Submitted - 1502.06617v4.pdf